The continuing development of portable electrically powered devices such as tape recorders and playback machines, radio transmitters and receivers, and the like, creates a continuing demand for the development of reliable, long service life cells or batteries for their operation. Recently developed electrochemical cell systems that will provide a long service life utilize highly reactive anode materials such as lithium, sodium, and the like, in conjunction with high energy density liquid cathode materials and nonaqueous electrolytes. However, the conventional cyclindrical cell structures are not ideally suited for the components of these high energy cell systems. For example, in a cylindrical cell, if the anode is disposed in contact with the inner surface of the cell casing and spaced apart a fixed distance from a centrally located cathode collector by a conventional separator member, then although good contact can be provided between these components when they are assembled in the cell, the contact between these components will decrease as the anode dissolves during discharge. Consequently, the dissolving of the anode during discharge will decrease the volume of the anode and thus tend to increase the distance between the anode and the separator/cathode collector components of the cell thereby decreasing the contact between these components which will result in an increase of the internal resistance of the cell.
To overcome the above disadvantage when using the components of such high energy density cell systems, it has been proposed that the components be assembled in rolled or coiled electrode assemblies (jelly roll construction) which would ensure good contact between the components of the cell during discharge. This type of cell construction is disclosed in U.S. Pat. No. 3,809,580 and in U.S. application Ser. No. 563,321 by D. H. Johnson filed Mar. 31, 1975. Although the jelly roll construction is suitable for liquid cathode cell systems, jelly roll cells are rather expensive to make and time consuming to fabricate and assemble.
U.S. Pat. No. 3,796,606 discloses a cylindrical electrochemical cell whose positive electrode is in contact with the outer casing of the cell and separated by a porous separator from a negative electrode constituted by a sheet of metal having a very negative standard oxidation potential surrounding an elastically deformable current collector having a split cylindrical shape in which the elasticity of the current collector enables it to maintain biased contact with the negative electrode at all times notwithstanding alteration in electrode volumes during discharge of the cell and thus to maintain the reacting surfaces of the solid positive and negative electrodes at optimum distances by continuously biasing the negative electrode against the porous separator.
It is an object of this invention to provide an electrochemical cell employing a liquid active cathode material in conjunction with an active metal anode and an elastically deformable carbonaceous cathode collector in the form of a slotted annular bobbin.
It is another object of the present invention to provide a nonaqueous cylindrical cell employing an elastically deformable carbonaceous cathode collector in the form of a slotted annular bobbin having a screen or like spring member longitudinally embedded within said bobbin so as to bias the bobbin radially outward and thereby maintain the anode, separator and cathode collector of the cell in good physical and electrical contact.
It is another object of the present invention to provide a nonaqueous cylindrical cell having component parts easy to assemble and which will exhibit a relatively low internal cell resistance during discharge.
The foregoing and additional objects will become more fully apparent from the following description and the accompanying drawings.